Trigger for machine guns



March 28, 1939. j gcHH p 2,151,708

' TRIGGER FOR MACHINE GUNS Filed March 2, 1938 Inventor duhnI;.I.mchhgac1 Attnrnay Patented Mar. 28, 1939 UNITED STATES 8 Claims.

(Granted under the act of March 3, 1 883, as amended April 30, 1928; 3700. G. 757) The invention described herein may be manufactured and usedby or for the Government for governmental purposes, without the paymentto me of any royalty thereon.

This invention relates to a trigger for machine guns.

The Browning machine gun as shown in Patent No. 2,050,538 of August 11,1936, is provided with a trigger in the form of a simple lever whichprovides for automatic firing so long as it is held in the firingposition. Firing is interrupted only by releasing the trigger, but dueto rapid action of the gun it is impossible to control single-shotfiring.

The purpose of this invention is to provide a trigger mechanism which issimple and inexpensive, which may be readily installed to replace thepresent Browning trigger without modifying its normal action, and whichin operation maintains the throw, pull and all characteristics of thepresent trigger.

These purposes are accomplished by providing a trigger mechanism in theform of a compound lever which includes a link normally connectingelements of the mechanism and arranged to be disconnected therefrom bythe reciprocating breech bolt of the gun.

To these and other ends, the invention consists in the construction,arrangement and combination of elements described hereinafter andpointed out in the claims forming a part of this specification.

A practical embodiment of the invention is illustrated in theaccompanying drawing, where- Fig. 1 is a View partly in side elevationand partly in section of the rear portion of a Browning gun showing thetrigger mechanism in the neutral position;

Fig. 2 is a view in rear elevation;

Fig. 3 is a plan view;

Figs. 4, 5 and 6 are detail views in side elevation showing the partsrespectively in neutral, fired and disconnected positions when themechanism is arranged for semi-automatic firing;

Fig. 7 is a view showing the adjustment for automatic firing.

Referring to the drawing by characters of reference there is shown aportion of a machine gun of the Browning type including a receiver Ahaving a back plate B, handle C, and a reciprocating breech bolt D whichcarries a sear E engageable with the firing pin F and actuated by atrigger bar G pivotally mounted in the receiver.

' The improved trigger mechanism is carried by the back plate B in thesame manner as the conventional trigger. It consists generally of a handtrigger 5, a trigger lever 6 for engaging the bar G, and a link 1 forconnecting the trigger and lever. The trigger 5 to which is fixed a fin-5 ger piece 8 has a bifurcated front end 9 which is disposed in a slotIt) in the back plate and is rotatably mounted on a pin I! carried bythe back plate and extending transversely of the slot. The under side ofeach division of the bifurcated end 9 is notched to provide a projectingfinger I2.

The lever 6 is rotatably mounted on the pin H within the bifurcated end9 and includes a rearwardly extending arm I 3 and a downwardly extendingarm H! of greater width than the arm I3 and adapted to engage the bar G.The arm 14 is normally held away from the bar G and against the innerside of the back plate by means of a helical spring 15 confined betweensaid arm and the top plate of the receiver.

The link i which is rotatably mounted on a pin l6 carried by the arm l3of the lever B includes a downwardly extending arm ll positioned in rearof the back plate and spaced arms [8 extending forwardly into the slotl0 and underneath the front end 9 of the trigger. Ea'ch arm l8terminates in a finger l9 which is adapted to be normally disposed infront of the corresponding finger l2 of the trigger when the rearportions of the trigger and link are separated by a helical spring 20.This engagement of the fingers limits separation of the trigger and linkunder the influence of the spring and establishes a driving connectionbetween them when pressure is applied to the trigger to depress it.

The arm ll of the link carries a housing 2| whose front portion isprovided with a diametral slot 22 andis arranged to move through anaperture 23 in the back plate. A rod 24 passing 40 through the housingand arm has a head 25 on its front end which is adapted to one positionof adjustment (Figs. 4-6) to engage the front face of the housing andserve to increase the effective length of the rod and in anotherposition of adjustment (Fig. 7) which is established by rotating itthrough ninety degrees to be receivedin the slot 22 of the housing. Athumb nut 26 is threaded on the rear end of the rod 23 and a spring 21embracing the rod and confined between the thumb nut and the rear faceof the arm ll of the link, serves to hold the rod in position ofadjustment.

In Figs. 1 and 4 the trigger mechanism is shown in the neutral orunfired position, the head 25 on the rod 24 being adjusted to providefor semiautomatic firing. When pressure is applied to the finger piece 8the trigger 5 is depressed and by virtue of the engagement of thefingers I2 and I9 the link I connects the trigger 5 and lever 6 andthese members are rotated as a unit about the pin I I as shown in Fig 5.

In this firing position the lever 6 trips the bar G which depresses thesear E and fires the gun. The head 25 carried by the link has been movedthrough the back plate and is now disposed in the path of movement ofthe reciprocating breech bolt D.

Upon firing of the gun the breech bolt is moved rearwardly and at theend of its recoil stroke it strikes the head 25 and swings the linkabout its pivot pin I6 to disconnect it from the trigger 5 by moving thefingers I9 below and out of the path of the fingers I2 of the trigger.As soon as the fingers are disengaged, the spring I5 which is strongerthan the spring restores the lever 6 to neutral position and in so doingthe pin I6 carried by the lever 5 moves about the pin II as a center andis thereby displaced sufiiciently to the rear so that the upper surfacesof the fingers I9 will engage the lower surfaces of the fingers I2 asshown in Fig. 6. So long as pressure is exerted on the trigger to holdit in depressed position this relationship of the fingers will bemaintained and the spring 29 will remain compressed, The lever 6 nolonger exerts pressure on the bar G so that when the breech bolt returnsinto battery the sear E will not be actuated to release the firing pin Ffrom cocked position.

In order to reestablish an operative relationship of the parts it isnecessary to relieve pressure on the trigger 5 whereupon the spring 20acts to separate the rear ends of the trigger and link and enable thefingers I2 of the trigger to reengage the fingers I9 of the link. Theparts are now in the position shown in Fig. 4 and in order to fire thenext shot the trigger must be depressed.

When it is desired to fire automatically the rod 24 is partially rotatedto align the head 25 and the slot 22 and enable the spring 21 to retractthe rod, the head entering the slot. In this position of adjustment ofthe parts the head 25 will not be struck by the breech bolt D when themecha-- nism is moved as a unit into firing position.

A spring 28 is carried by a portion of the back plate and engages thefinger piece 8 to normally hold it in safe or unfired position.

I claim:

1. In a machine gun, a receiver having a back plate with a slot and anaperture, a reciprocal breech bolt in the receiver, a sear in the breechbolt, a trigger bar for operating the sear, a pin in the back platetransversely of the slot therein, a trigger having a bifurcated frontend pivotally mounted on the pin, each division of said front end havinga projecting finger on its lower side, a lever pivotally mounted on thepin within the bifurcated end of the trigger, said lever including adepending arm adapted to actuate the trigger bar, a spring acting on thelever to hold the, arm away from the trigger bar and against the backplate, a link pivotally mounted on the lever and having spaced arms eachwith a finger engageable with the correspondingly positioned finger ofthe, trigger, a spring between the trigger and link and normallymaintaining. them connected through their fingers, a depending arm onthe link, and means adjustable for length carried by the link andmovable through the aperture in the back plate, said means in oneposition of adjustment engageable by the breech bolt to disconnect thelink from the trigger.

2. In a machine gun, a receiver having a back plate, a reciprocal breechbolt in the receiver, a scar in the breech bolt, a trigger bar foroperating the sear, a pin in the back plate, a trigger pivotally mountedon the pin and including a projecting finger, a lever pivotally mountedon the pin and including an arm adapted to actuate the trigger bar, aspring acting on the lever to hold the arm away from the trigger bar andagainst the back plate, a link pivotally mounted on the lever andincluding an arm with a finger engageable with the finger of thetrigger, a spring between the trigger and link and normally maintainingthem connected through their fingers, a depending arm on the link, andmeans adjustable for length carried by the link and movable through theback plate, said means in one position of adjustment engageable by thebreech bolt to disconnect the link from the trigger.

3. In a machine gun, a receiver having a back plate, a reciprocal breechbolt in the receiver, a sear in the breech bolt, a trigger bar foroperating the sear, a pin in the back plate, a trigger pivotally mountedon the pin and including a projecting finger, a lever pivotally mountedon the pin and including an arm adapted to actuate the trigger bar, aspring acting on the lever to hold the arm away from the trigger bar andagainst the back plate, a link pivotally mounted on the lever andincluding an arm with a finger engageable with the finger of thetrigger, a spring between the trigger and link and normally maintainingthem connected through their fingers, and means whereby the link isengageable by the breech bolt to disconnect it from the trigger.

4. In a machinegun, a receiver having a back plate, a reciprocal breechbolt in the receiver, a sear in the breech bolt, a trigger bar foroperating the sear, a trigger pivotally mounted on the back plate andincluding a projecting finger, a lever pivotally mounted on the backplate and adapted to actuate the trigger bar, a spring acting on thelever to hold it away from the trigger bar, a link pivotally mounted onthe lever and including a projecting finger engageable with the fingerof the trigger,,a spring between the trigger and link and normallymaintaining them connected through their fingers, and means carried bythe link and positionable to be engaged by the breech bolt to disconnectthe link from the trigger.

5. In a machine gun, a receiver, a reciprocal breech boltin thereceiver, a trigger bar mounted on the receiver, a trigger pivotallymounted on 'the receiver, a lever pivotally mounted on the receiver andadapted to actuate the trigger bar, a spring for normally holding thelever away from the trigger bar, a link pivotally mounted on the leverand connectable and disconnectable with the trigger, a spring betweenthe triger and link and normally maintaining them connected, and meanscarried by the link and positionable to be engaged by the breech bolt todisconnect the link from the trigger.

6. In a machine gun, a receiver, a reciprocal breech bolt in thereceiver, a trigger bar mounted on the receiver, a trigger pivotallymounted on the receiver a lever pivotally mounted on the receiver andadapted to actuate the trigger bar, a link carried by the lever andnormally coupling the trigger and lever whereby they are movable as aunit, said link arranged to be engaged by the breech bolt to uncouplethe trigger and lever.

7. In a machine gun, a receiver, a reciprocal breech bolt in thereceiver, a trigger bar mounted on the receiver, a trigger pivotallymounted on the receiver, a lever pivotally mounted on the receiver andadapted to actuate the trigger bar, and means normally coupling thetrigger and lever whereby they are movable as a unit, said meansadjustable to be selectively clear of and engageable by the breech boltand when engaged by the breech bolt to uncouple the trigger and lever.

8. In a machine gun, a receiver, a reciprocal breech bolt in thereceiver, a trigger bar mounted on the receiver, a trigger pivotallymounted on the receiver, a lever pivotally mounted on the reoeiver andadapted to actuate the trigger bar, and means normally coupling thetrigger and lever whereby they are movable as a unit, said meansengageable by the breech bolt to uncouple 10 the trigger and lever.

JOHN L. LOCHHEAD.

